Compressed gas engines are, of course, known. These somewhat resemble a conventional internal combustion engine in that they typically have a piston mounted for reciprocating movement within a cylinder. Compressed gas from a suitable source is arranged to be selectively admitted into the chamber, to expand the volume of same, and to drive the piston downwardly toward its bottom dead center position. When the piston approaches the downward limit of its power stroke, gas within the chamber is selectively vented. Various types of prior art compressed gas engines are shown and described in Pond, Expansion Engine Powered Model Aircraft, AMA-915, SAM-376.
In prior art compressed gas engines, particularly those of simple design, there was a problem with the sealing integrity of valves used to selectively admit compressed gas from the source to the chamber. The principal problem was such valves were accompanied by substantial leakage, which reduced the overall efficiency of the engine. Furthermore, scavenging of spent residual gases in the cylinder, needed in prior art designs to obtain power efficiency, adds complexity and reduces gas use efficiency.
The present invention provides an improved gas engine which overcomes these problems in the prior art by providing an improved valve with positive sealing features to control the selective admission of gas into the variable-volume chamber, and which provides for reduction in recompression effects during the piston return stroke.